This invention relates generally to a system and method for performing less-invasive surgical procedures, and more specifically, to a system and method for isolating a surgical site such as the site of an anastomosis of a graft vessel and a coronary artery in a thoracoscopic coronary artery bypass grafting procedure.
In coronary artery disease, the build-up of artherosclerotic plaque on the inner walls of the coronary arteries causes a narrowing or complete closure of these arteries, resulting in insufficient blood flow to the heart. This condition has become one of the most common life-threatening medical problems facing older men and women.
A number of approaches have been developed for treating coronary artery disease. In less severe cases, it is often sufficient to treat the symptoms with pharmaceuticals and lifestyle modification to lessen the underlying causes of the disease. In more severe cases, a coronary artery blockage can often be treated using endovascular techniques such as balloon angioplasty, atherectomy, laser or hot tip ablation, placement of stents, and the like.
In cases where pharmaceutical treatment and/or endovascular approaches have failed or are likely to fail, it is often necessary to perform a coronary artery bypass graft procedure using open surgical methods. Such methods require that the patient""s sternum be divided longitudinally and the chest be spread apart to provide access to the heart, known as a median sternotomy. The patient""s heart is placed under cardioplegic arrest and the patient is supported by cardiopulmonary bypass. A source of arterial blood is then connected to the diseased coronary artery downstream from the blockage. The arterial blood source may be a venous or arterial graft vessel connected between an arterial blood vessel such as the aorta and the coronary artery. Another common arterial blood source is either the left or right internal mammary artery which may be grafted to the coronary artery which is narrowed or occluded. Recent studies have suggested that the use of the mammary arteries as an arterial blood source may be advantageous over other sources due to a greater likelihood that the graft will remain patent over time.
To form an anastomosis between an internal mammary artery and a coronary artery, blood flow through the internal mammary artery must be temporarily stopped, typically by applying a removable clamp to the mammary artery. The mammary artery is then severed downstream from the clamp to create a free end. An incision is created in the target coronary artery downstream of the blockage. The free end of the mammary artery can then be connected to the incision in the coronary artery, typically by suturing, such that blood can flow from the mammary artery through the incision into the coronary artery.
To facilitate the surgeon""s view of the procedure, the heart must be positioned to expose the anastomosis site, and the anastomosis site must be cleared of fluids, tissue and debris which may obscure the site. In addition, the coronary artery or mammary artery may contain blood and other fluids near the location of the incision, which should be prevented from flowing out of the coronary artery or mammary artery during the suturing procedure. The coronary and mammary arteries must also be stabilized and held in a stationary position so that the surgeon can perform the delicate task of sewing the free end of the mammary artery to the coronary artery.
Using conventional open-chest methods, the anastomosis procedure is typically performed directly through the large opening in the patient""s chest provided by a median sternotomy. This opening enables the surgeon to see the coronary and mammary arteries directly and to position his or her hands within the chest cavity in close proximity to these arteries for manipulation of surgical instruments. The surgeon can thus utilize various instruments to reposition the heart, clear away fluid and debris and stabilize the anastomosis site during the procedure. For example, clamps may be applied to the mammary and coronary vessels to stop blood from leaking from these vessels. If tissue or fluids migrate into the anastomosis site, the surgeon can utilize an irrigation tube to wash these obstructions away from the site. The heart may be repositioned using retraction devices or simply by hand. To stabilize the mammary artery during the anastomosis, a pair of forceps can be used to grasp the mammary artery and maintain its position while it is sewn to the coronary artery. All of these tasks are accomplished without great difficulty due to the open exposure of the surgical site through the large opening provided by a median sternotomy.
While open-chest coronary artery bypass grafting is very effective in many cases, the gross thoracotomies used in conventional open heart surgery to perform coronary artery bypass grafting are highly traumatic to the patient. Therefore, new methods of performing surgery on the heart using minimally invasive thoracoscopic techniques have been recently developed. In these methods, the patient""s heart is arrested by occluding the patient""s aorta between the coronary arteries and the brachiocephalic artery with an expandable balloon on the distal end of an endovascular catheter introduced via a femoral artery. Cardioplegic fluid is then delivered to the patient""s myocardium through a lumen in the same catheter or through a separate catheter positioned in the coronary sinus. This method allows the surgeon to perform operations such as coronary artery bypass grafting without creating a large opening in the patient""s sternum. Minimally-invasive cutting and suturing instruments can be introduced thoracoscopically to connect the free end of the severed mammary artery to the coronary artery. Complete descriptions of such methods are found in commonly assigned, co-pending application Ser. No. 08/023,778, filed Feb. 22, 1993, and application Ser. No. 08/194,946, filed Feb. 11, 1994, which are incorporated herein by reference.
The new generation of thoracoscopic methods of performing coronary artery bypass grafting has, of course, created many new challenges. Such challenges include keeping the anastomosis site free of fluid and debris, positioning the heart within view of the surgeon(s), and stabilizing the coronary and mammary arteries to facilitate the anastomosis. These functions must be performed through small percutaneous incisions or cannulae positioned in intercostal spaces in the patient""s rib cage. Known devices are not capable of performing these tasks through small percutaneous penetrations and, therefore, are unsuitable for closed chest procedures.
For this reason, improved systems and methods are desired for isolating a surgical site, such as an opening in a fluid-carrying vessel, in a body cavity via a small percutaneous incision or cannula. Preferably, the system and method would be capable of isolating a site of an anastomosis between a coronary artery and a mammary artery during a coronary artery bypass grafting procedure. The system and method should allow the surgeon to apply pressure against a vessel on both sides of an opening or incision in the vessel to inhibit blood and other fluids from passing through the incision. The system and method should also allow the surgeon to stabilize the mammary artery to facilitate suturing the free end of the mammary artery to the coronary artery. The system and method should further allow the delivery of irrigation fluids to the surgical site to wash away fluid and debris. In addition, it would be desirable if the above functions were performed by a single instrument introduced through a cannula or small percutaneous incision to limit the number of incisions required to perform the procedure.
The present invention provides an endoscopic device and method for isolating a surgical site, such as an opening in a fluid-carrying vessel, through a small, percutaneous penetration in the patient. The invention allows the surgeon to position a contact surface against a vessel and exert pressure against the vessel to inhibit blood and other fluids from flowing through an opening in the vessel. The contact surface is also adapted to stabilize a second vessel for attachment to the first vessel. In addition, the invention may be used to hold an end of a suture while performing a surgical procedure such as an anastomosis. The invention further allows the delivery of an irrigation fluid to the surgical site to clear away blood and debris. The system is particularly suited for forming an anastomosis between a coronary artery and an internal mammary artery in a thoracoscopic coronary artery bypass procedure. While being especially suited for thoracoscopic procedures, the system and method of the invention are also useful in other surgical procedures, such as laparoscopic, endoscopic and arthroscopic procedures, as well as in conventional open surgical procedures.
In one aspect of the invention, the system comprises a shaft having a proximal end and a distal end configured for delivery through a small, percutaneous penetration. A foot, configured for engaging a tissue structure such as a blood vessel, is pivotally coupled to the distal end of the shaft. The foot has first and second engaging portions separated by a gap. The engaging portions each have a contact surface for engaging the tissue structure such that a surgical site on the tissue structure is disposed in the gap. A linkage is coupled to the foot, and an actuator means. coupled to the proximal end of the shaft, actuates the linkage to pivot the foot about a transverse axis so that the contact surfaces may be oriented generally parallel to the surface of the tissue structure. This allows the surgeon to apply pressure to the tissue structure on two sides of the surgical site
The tissue structure may be, for example, a blood vessel to which a second blood vessel is to be attached in an anastomosis procedure. An opening will be formed in the blood vessel to which the second blood vessel is to be connected. The first and second engaging portions of the foot may be positioned so that the opening in the blood vessel is disposed in the gap. In this way, the contact surfaces on the engaging portions may be pressed against the blood vessel to close the vessel lumen, thereby stopping the flow of blood and other fluids through the opening. At the same time, the foot stabilizes the blood vessel to maintain its position during the procedure. Additionally, the second blood vessel may be positioned under one or both contact surfaces to hold it in position as it is attached to the other vessel. Further, the foot may be used to reposition the blood vessel to improve access and/or visibility of the surgical site.
In a preferred embodiment, the linkage includes a longitudinal rod slidably disposed within an axial lumen in the shaft and having proximal and distal ends. The proximal end of the rod is coupled to the actuator means and the distal end of the rod is coupled to the foot. The foot is coupled to the shaft at a pivot point and to the rod at a coupling point separated from the pivot point. Axial movement of the rod with respect to the shaft rotates the foot about the pivot point. Preferably, the foot can pivot more than 90 degrees about the transverse axis so that the surgeon can approach the surgical site from various directions.
The actuator means is configured to pivot the foot about the transverse axis from a first position, where the foot is configured for delivery through a percutaneous penetration, to a second position, where the contact surfaces are oriented generally parallel to the surgical site. In an exemplary embodiment, the actuator means comprises a knob threadably coupled to the proximal end of the shaft. The knob is fixed to the proximal end of the rod so that rotation of the knob moves the knob and the rod in an axial direction with respect to the shaft.
In one embodiment, the foot comprises first and second arms extending distally from the distal end of the shaft. The arms are movable between an open configuration, where the arms are disposed apart, and a collapsed configuration, where the arms are disposed closer together. In the open configuration, the arms form a xe2x80x9cVxe2x80x9d shape and are configured to engage the blood vessel on both sides of the opening. In the collapsed configuration, the arms are substantially parallel so that the foot is configured for delivery through a percutaneous penetration in the patient""s body. The arms may be biased into the open configuration by a spring, or an actuator may be used for moving the arms between the open and collapsed configurations.
In a second embodiment, the foot comprises an annular ring with an inner hole. The hole preferably has a diameter larger than the opening in the vessel so that the annular ring can engage the vessel on both sides of the opening without obstructing the opening. Preferably, the annular ring is made of a flexible material so that it can be collapsed into a configuration suitable for introduction through a percutaneous penetration. Alternatively, the annular ring includes a hinge so that the ring can be folded into a collapsed configuration.
The invention may further include means for retaining a suture in contact with the foot. Preferably, the suture retaining means is a plurality of slots formed in upper surfaces of the foot for frictionally engaging the suture. The suture will include first and second free ends each connected to a needle. The first free end may be placed in and retained by one of the slots while the surgeon manipulates the second free end. The second free end may then be placed in and retained by one of the slots while the surgeon utilizes the first free end. If desired, the surgeon can apply tension to the suture by rotating the foot. This allows the surgeon to reposition or stabilize the surgical site during the operation.
For the purpose of removing fluids and debris from the surgical site, the shaft includes an irrigation lumen extending between the distal and proximal ends and the foot includes a plurality of holes fluidly coupled to the lumen at the distal end. The proximal end of the lumen is configured for being coupled to a source of irrigation fluid to allow the fluid to be delivered under positive pressure through the lumen and through the holes in the foot to the surgical site. The holes are preferably configured and positioned to direct irrigation fluid into the gap between the first and second engaging portions to clear fluid and debris from the surgical site. If desired, a reservoir of fluid can be created within the hole in the annular ring to submerge the surgical site in fluid during the surgical procedure.
The invention is also useful for repositioning an organ in a body cavity to facilitate a surgical procedure. For example, the invention is useful for repositioning the heart in a coronary artery bypass grafting procedure. To reposition the heart, the foot is introduced through a percutaneous incision or trocar sleeve and pivoted relative to the shaft so that the contact surfaces are generally parallel to the external surface of the heart. Preferably, the contact surfaces on the arms of the foot have an arcuate portion that generally conforms to the curvature of the heart. The surgeon then applies a force to the foot to frictionally engage the heart and reposition it to the desired location for the surgical procedure. To reduce the risk of damaging the heart and to augment the frictional contact force, an atraumatic high friction material, such as foam, may be attached to the contact surfaces.
The invention is particularly useful for isolating an anastomosis site between a coronary artery and an internal mammary artery during a cardiac procedure such as coronary artery bypass grafting. In this procedure, the patient""s heart is placed under cardioplegic arrest and the patient is supported by cardiopulmonary bypass. Several cannulae are positioned in percutaneous intercostal penetrations in the left anterior chest of the patient. A viewing scope is introduced through another left anterior percutaneous intercostal penetration. A small incision is made in the left lateral chest, through which instruments are introduced to dissect a portion of a mammary artery away from the chest wall. The mammary artery is clamped and then severed to create a free end downstream of the clamp. An incision is created in the coronary artery corresponding to the size of the free end of the mammary artery.
Once the mammary and coronary arteries are prepared for the anastomosis, the engaging portions of the foot are moved into the collapsed configuration and introduced through the cannula. After the foot has passed through the cannula, the engaging portions are biased back into the open configuration. The knob is then rotated to actuate the linkage and pivot the foot such that the contact surfaces are generally parallel to the surface of the heart and the wall of the target coronary artery. The shaft is advanced distally until the contact surfaces engage the coronary artery so that the incision in the artery lies in a gap between the arms. Although normal blood flow through the coronary artery will have stopped since the heart will have been placed under cardioplegic arrest, the cardioplegic fluid used to stop the heart may continue to flow through the coronary arteries during the procedure. The foot is pressed against the artery with sufficient force to inhibit fluids from flowing through the incision in the coronary artery. Preferably, a free end of the mammary artery is also placed under the contact surface of the foot to stabilize the mammary artery and hold the free end in a stationary position with respect to the incision in the coronary artery.
A suture is then introduced to sew the free end of the mammary artery to the coronary artery. To facilitate the operation, the first free end of the suture can be retained in one of the slots on the foot while suturing the vessels with the second free end. During the operation, fluid may be periodically delivered through the irrigation lumen and the holes in the foot to wash away fluids and other debris that may have migrated into the anastomosis site. If desired, a reservoir of fluid may be maintained on the wall of the heart between the contact portions of the foot to keep the opening in the coronary artery submerged during the procedure, thereby preventing the introduction of air into the coronary arteries. After the anastomosis has been completed, the foot is withdrawn from the surgical site and removed from the patient""s body through the cannula.
It should be understood that while the invention is described in the context of thoracoscopic surgery of the heart, the system and method disclosed herein are equally useful in other types of surgery, e.g. surgery on vessels and organs within the abdomen or pelvis.
A further understanding of the nature and advantages of the invention may be realized by reference to the remaining portions of the specification and the drawings.